Victor Oancea

A Computationally Efficient and Accurate Lumbar Spine Model

The design of spine implants requires a good understanding of spine kinematics and loading conditions. Realistic simulation of each functional spinal unit (FSU) requires capturing complicated contact and deformation of biological tissues in a computationally efficient manner. Specifically, the complexities include contacts in intervertebral and facet joints, restraints of spine ligaments, as well as realistic material properties of soft tissues. The variation in the stiffness among different FSUs is often neglected in spine modeling, which might be crucial for spine function. A hybrid approach for lumbar spine modeling was established that combined motion capture experiments, kinematic spine modeling and detailed finite element modeling. Motion capture data during flexion was collected and used to drive the spine model. For computational efficiency each FSU was modeled as an intervertebral connector (joint) element with different elastic behavior at each level. The connector behavior was calibrated using experimental data on the whole lumbar spinal motion (Wong et al. 2006) and cadaveric moment-rotation relationship of L45 (Heurer et al. 2007). Then the predicted stiffness for L23 was used to calibrate the material properties of a detailed FEM of L23.Copyright

Development of a New Finite Element Model in Abaqus for the WorldSID 50

This paper describes the modeling and validation of the new WorldSID 50th percentile male dummy (WorldSID50) model for the Abaqus finite element (FE) software suite [1]. The Abaqus WorldSID50 model has been developed by Dassault Systemes Simulia Corp. in cooperation with the Partnership for Dummy Technology and Biomechanics (PDB), a consortium that includes the following German automobile manufacturers: Audi, BMW, Daimler, Porsche, and Volkswagen. The objective of the dummy development project was to develop a robust virtual dummy model that closely mimics the behavior of the hardware dummy in order to minimize the need for physical testing during vehicle design. Data obtained through extensive experimental tests performed at all levels of the dummy assembly — material coupon, component, sub-assembly, and full dummy — were used to calibrate and validate the finite element model. The Abaqus WorldSID50 model results show good correlation with the hardware dummy output signals for a wide range of tests. The Abaqus WorldSID50 model was approved for use in production by the PDB.Copyright

Development of a New Finite Element Model for the BioRID II Crash Dummy

This paper describes how the Biofidelic Rear Impact Dummy (BioRID-II) has been developed as a testing tool to measure automotive seat and head restraint system performance in low-speed, rear-end crashes and to help with understanding of whiplash neck injuries. The paper focuses on the current Abaqus BioRID-II model which has been developed by Dassault Systemes Simulia Corp. (SIMULIA) in cooperation with the German Association for Research in Automobile Technology FAT, utilizing an extensive suite of material, component and full dummy experiments in the universal Chalmers seat in order to calibrate and validate the model response. The Abaqus BioRID-II model uses connector elements extensively to model complex connections and instrumentation, and to help improve runtime efficiency by reducing the number of degrees of freedom in the model. The assembly process for the actual BioRID-II dummy introduces nontrivial initial deformations and stresses in the critical components of the neck and spine, which must be accounted for in the model itself; the Abaqus BioRID-II model leverages both the explicit and the implicit solution techniques available in the Abaqus product suite to accomplish this. Finally, a comparison between Abaqus simulation results against available experimental test data is included in the paper, suggesting the usefulness of the model in evaluating dummy response and seat performance. Although the responses of most of the variables monitored in the Abaqus dummy are matching well the experimental responses, the authors would like to underline that this paper presents the current development status of this dummy and that there is an ongoing effort to improve its quality.